The byssal adhesive of the marine mussel, Mytilus edulis, is an ideal system for studying requirements for adhesion under water. There are four major components in the byssus: polyphenolic substance, collagen, beta-protein and mucosubstance. Each of these is secreted from an exocrine gland in the foot whereupon they are blended with one another, and the amalgam is tanned by the action of phenoloxidase. My specific aims are to 1) isolate the polyphenolic substance, a DOPA-containing protein from the phenol gland, and determine the location of DOPA in tryptic peptides by sequence analysis; 2) characterize the physical and chemical properties of byssal collagen using electrophoresis, ion exchange chromatography, viscometry and circular dichroism; 3) purify the beta-protein from the accessory gland using SP-Sephadex ion exchanger, and determine its molecular weight by electrophoresis and gel filtration and structure by quantifying the number of disulfide bonds and the degree of beta conformation (using circular dichroism); 4) determine whether the mucosubstance is a sulfate-containing molecule by labelling animals with 35SO4 and analyzing secreted byssal proteins by gel electrophoresis and autoradiography. Studying the byssal adhesive is valuable not only with regard to its possible application to the restoration of fractured hard tissues, but also for its relevance to the synthesis and design of other effective bioadhesives.